Editing Ganzfeld experiment (section)

==Experimental procedure==
In a typical Ganzfeld experiment, a "receiver" is placed in a room relaxing in a comfortable chair with halved ping-pong balls over the eyes, having a red light shone on them. The receiver also wears a set of headphones through which [[white noise|white]] or [[pink noise]] (static) is played. The receiver is in this state of mild sensory deprivation for half an hour. During this time, a "sender" observes a randomly chosen target and tries to mentally send this information to the receiver. The receiver speaks out loud during the 30 minutes, describing what they can "see". The experimenter, who knows nothing of the chosen target, records these comments either on audiotape or through written notes.

Once time expires, the receiver is taken out of the Ganzfeld state and shown a set of possible targets, from which they select one which most resembles the images they witnessed. The receiver may refer to the notes/recordings made by the experimenter as needed. Most commonly there are three decoys along with the target, giving an expected rate of 25%, by chance, over several dozens of trials.<ref>{{cite journal | title=ESP in the Ganzfeld | author=Palmer, John | journal=Journal of Consciousness Studies | volume=10 | issue= 6–7 | year=2003}}</ref>

Some parapsychologists who accept the existence of psi have proposed that certain [[Trait theory|personality traits]] can enhance ESP performance.<ref name="BemHonorton1994">{{cite journal |last=Bem |first=Daryl J. |author2=Honorton, Charles |year=1994 |title=Does psi exist? Replicable evidence for an anomalous process of information transfer |url=http://www.dbem.ws/Does%20Psi%20Exist%3F.pdf |url-status=dead |journal=Psychological Bulletin |volume=115 |issue=1 |pages=4–18 |doi=10.1037/0033-2909.115.1.4 |archive-url=https://web.archive.org/web/20170317150522/http://www.dbem.ws/Does%20Psi%20Exist?.pdf |archive-date=2017-03-17 |access-date=2007-07-31}}</ref> Such parapsychologists have argued that certain characteristics in the participants could be selected for that would increase the scores of ganzfeld experiments.<ref name="StormEtAl2010" /> Such traits have included the following:
* Positive belief in psi; ESP<ref name="Lawrence1993">{{cite journal |author=Lawrence, T.R. |year=1993 |title=Gathering in the sheep and goats: A meta-analysis of forced-choice sheep-goat ESP studies, 1947–1993 |journal=In Proceedings of the 36th Annual Convention of the Parapsychological Association |pages=75–86}}</ref>
* Prior psi experiences<ref name="BemHonorton1994" />
* Practicing a mental discipline such as meditation<ref name="BemEtAl2001" />
* Creativity<ref name="BemHonorton1994" />
* Artistic ability<ref name="BemHonorton1994" />
* Emotional closeness with the sender<ref name="Broughton1997">{{cite journal |author1=Broughton, R.S. |author2=Alexander, C.H. |year=1997 |title=AutoganzfeldII: An attempted replication of the PRL ganzfeld research |journal=Journal of Parapsychology |volume=61 |pages=209–226}}</ref>

Critics have pointed out that relying on selection criteria like this can introduce bias in the experimental design, and so generally discussion of any claimed effects has typically included only studies that sample normal populations rather than selecting for "special" participants (see below).<ref name="StormEtAl2010" />